1. Field of the Invention
A work holder including two or more jaws movable with respect to each other, and more particularly a screw-less, quick-action vise assembly.
2. Related Art
Woodworking workbenches have traditionally employed a vise or vises for gripping workpieces. The vises utilized have taken many different forms which suit a wide array of woodworking tasks. Face vises, mounted on the front or long face of the workbench may be in the form of a twin screw face vise with the screws coupled by a chain or where the screws are independent. They also take the form of cast iron Emmert style vises which have pivoting jaws to accept tapered or irregular shaped work or the quick action Record style of vise which typically have a central screw combined with two laterally displaced guide rods. Another form of face vise is the leg vise which utilizes a screw mounted in one of the workbench legs with a vertically displaced fulcrum arm which accepts a peg installed in a hole to match the thickness of the work being secured. Face vises may also be in the form of the Scandinavian style shoulder vise which has a vise screw installed in a bench block mounted at the end of the bench and typically supported by an additional leg. The vise jaw is open to three sides so it has the ability to clamp work that would be difficult to clamp in the other style of vises.
Vises may also be found mounted to the end of the bench in the form of a tail vise. Typically the tail vise includes a dog which may be used to clamp work flat on the bench top between a corresponding bench dog mounted in various holes in the top of the bench. Many of the previously described face vises may be mounted on the end of the bench to function as a tail vise. The twin screw vise for example may be mounted on the end of the bench and be the same width as the bench top. If provisions are made in the vise jaw to accept bench dogs then the vise can function as a tail vise and still operate as a face vise mounted in the end or tail vise position.
All of the aforementioned vises excel at some tasks and have deficiencies which have to be overcome. Twin screw vises offer drop through clamping of large objects without racking since pressure is applied on both sides of the workpiece. The chain operated twin screw vise may have an external chain which detracts from the aesthetics of the work bench. The chain operated twin screw vises do not have quick action and have to be laboriously cranked in and out. The screws also require grease to work freely which may soil the workpiece if contacted. Independent operated twin screw vises also do not have quick action and require each screw to be operated while maintaining a grasp on the workpiece with the operators other hand. The iron style face vises may have quick action and are easy to install but the central screw and guide rods prevent drop through clamping. The vise jaws may rack if the work is not centered and the quick action nut may clog with dirt and sawdust preventing proper action. Some vises require the actuation of a lever to enable quick action which makes them difficult to operate and the screw requires grease which may soil the workpiece. Leg vises excel at clamping work to the front face of the bench and have great holding power due to the long fulcrum arm. They do not have quick action and a peg must be moved in the fulcrum arm each time a different thickness workpiece is clamped. The fulcrum arm is very near the floor and requires considerable bending to change. The Scandinavian style shoulder vise requires the vise to be designed into the bench since it requires an additional leg. They do not have quick action and the bench block and vise screw extending outward from the front of the bench can be awkward to move around. Traditional tail vises are aesthetically pleasing and work well but they are very difficult to install, do not have rapid action and may sag when extended.
Typically, all screw actuated vises operate with clockwise rotation of the clamp handle which ergonomically speaking may not be ideal for all operators. Left-handed people in particular may find that clockwise operation is not the best direction of rotation for them.
Screw-less, or so-called clutch-type, vises have been proposed as alternatives to the aforementioned traditional screw-type vise. Screw-less vises are, by nature, quick-acting in that the vise jaws can be quickly opened and closed with a pushing or pulling force on the vise handle. These type of vises commonly utilize one or more clutch plates that smoothly slide along an elongated clamp shaft when held in a perpendicular orientation. Partial rotation of the vise handle turns a helical ramp that is positioned to interact with the clutch plate. Relative movement between the helical ramp and clutch plate causes the clutch plate to tip away from perpendicular and grip the clamp shaft. Continued rotation of the vise handle then draws the vise jaws together into engagement with a work piece. Examples of screw-less vises may be seen in U.S. Pat. Nos. 831,919 to Abernathy, 1,283,192 to Hughes, 1,439,822 to Johnson, 2,415,303 to Moore, and 4,057,239 to Hopf et al. In all of these examples, the clutch plate is fashioned as a non-circular member constrained to a particular orientation relative to the shaft. As a result, the clutch plate and shaft do not rotate relative to one another, thus causing the clutch and/or shaft to wear unevenly over time. Furthermore, the helical ramp feature common to the prior art screw-less vises is relatively expensive to manufacture, limits the clamping direction to a single direction (typically CW), and makes the vise assembly relatively unsuitable for use in multi-shaft, i.e., ganged, scenarios found in many woodworking vise applications.